The major goals of this research proposal are to describe and analyze cardiovascular control mechanisms with particular emphasis on the autonomic nervous system in normal healthy conscious animals, instrumented for direct and instantaneous measurements and radiotelemetry of coronary and regional blood flows and vascular resistances, ventricular function and myocardial contractility. Miniature pressure gauges will be implanted in the left and right ventricles and aorta, ultrasonic dimension transducers will be opposed on the endocardial surfaces of the left ventricle and Doppler ultrasonic or electromagnetic flow probes will be placed on the ascending aorta, coronary, mesenteric, renal and iliac arteries. In order to achieve these goals several specific interlocking groups of projects are planned. First of all, the afferent limb of the autonomic nervous system controlling the circulation will be examined, e.g., regulation by arterial baroreceptors, chemoreceptors, pulmonary inflation receptors, and low pressure vagal afferents. Secondly efferent autonomic control of ventricular performance, the coronary circulation, and the regional circulations will be studied. Thirdly, autonomic control during exercise will be examined. Thus, the aim of this research proposal is to gain a clearer understanding of the control of the cardiovascular system by the autonomic nervous system in the normal conscious animal.